Today, the piloting stations of vehicles, in particular aircraft, are equipped with multiple piloting assistance devices, designed to assist the pilot in driving the vehicle by displaying information relative to the speed and altitude of the vehicle, information relative to the operation of apparatuses onboard the vehicle, or information on the environment of the vehicle.
These piloting assistance devices commonly comprise “head up display” (HUD) devices, situated at eye level for the pilot and displaying information superimposed on a view of the outside environment through the piloting assistance device, and “head down devices” (HDD), situated on the dashboard and for which the pilot must look away from the outside environment to read the displayed information.
To display the images superimposed on the view of the outside environment, head up display devices most often used head up collimators. These collimators generally comprise an image source, a collimator lens that infinitely returns the images generated by the source, and a combiner passed through by the radiation coming from the outside environment and the rays transmitted by the collimator lens. In the collimators, the image source is for example a cathode tube monochromatic display.
Head up display devices thus allow the pilot to see the displayed information while continuing to observe the outside environment. Furthermore, head up display devices make it possible to display information that enriches the view of the outside environment by the pilot, such as markers showing certain elements of the outside environment.